Synchronized piezoelectric and luminescence material and element including the same

ABSTRACT

There is provided a method of preparing a synchronized piezoelectric and luminescence material. The method includes mixing a solution (a) including light-emitting particles or precursors thereof and a solution (b) including ligands having a piezoelectric property in a polar solvent; and optionally, mixing a solution (c) including ligands having a piezoelectric property in an antisolvent together with the solution (a) and the solution (b), if necessary.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. patent applicationSer. No. 17/106,581 (filed on November 30, 2020), which claims priorityunder 35 U.S.C. § 119 to Korean Patent Application No. 10-2020-0100268(filed on August 11, 2020), which are all hereby incorporated byreference in their entirety.

BACKGROUND

The present invention relates to a synchronized piezoelectric andluminescence material and an element including the same, and moreparticularly, to a single synchronized piezoelectric and luminescence(SPL) material including light-emitting particles and ligands with apiezoelectric property to simultaneously have a piezoelectric propertyand a luminescent property, and an element using the same.

A hyper-connected society, in which future people, objects, and spacesare fused, requires electronics which may detect and display a varietyof further types of massive human sensory information and may beautomatically and constantly driven.

However, the current high integration electronic information (digitalcontent) processing methods through scaling (scaling-down orminiaturization) will soon reach a technical limit and will be expectedto be unable to meet processing demands for massive human informationdata in the future society. In addition, in the current high integrationmethods through miniaturization of elements that perform an independentfunction of detecting or displaying human sensory information, due tothe limitations of massive information processing as well as systemcomplexity and enlargement, weight, power consumption, and the like areincreased. Thus, the current highly integrated method is not verysuitable for electronics that are automatically and constantly drivenand human-friendly.

Therefore, in order to overcome the limitations of scaling technologythrough the current miniaturization and high-integration method, futureinformation communication technology (ICT) requires a new direction formultifunctionalization (functionality & diversification) that is capableof simultaneously performing functions of detecting and displaying humansensory information. However, current technology reaches only a level ofsimple stacking or compositing of an independent sensing element anddisplay element or an independent sensing element and display materialand thus does not beyond the limitations of integration technology.Accordingly, ultra-low power driving for constant driving is not easy.

Some artificial synesthesia elements, which use a speaker or microphoneand display fusion technology or sensor and display fusion technology inorder to detect and display human sensory information, have beenreported in academia, but the artificial synesthesia element is anelement in which separate elements are connected through amicroprocessor or two or more elements are formed in the form of astack. Recently, research is being conducted to prepare materials, whicheach play a certain role, in a composite form, but ultimately, in orderto overcome the limitations of ultra-low power and ultra-thin films ofwearable devices, it is ideal that one element or one material performsmultiple sensing, switching, and displaying.

Accordingly, in order to implement an ultra-low power artificialsynesthesia element that can be constantly driven, it is first necessaryto develop an ultra-lightweight material for ultra-low power drivingabove all else, and the most ideal method is a method of combiningmechanical and optical elements at a molecular level within a singlematerial. In terms of materials, a mechanical function of artificialsynesthesia can be implemented using a dielectric piezoelectricmaterial, and an optical function thereof can be implemented using asemiconductor light-emitting material. In particular, in the case of thepiezoelectric material, a self-generating property thereof capable ofgenerating electricity by external stress enables the implementation ofan artificial synesthesia element for constant powerless driving. Asdescribed above, an artificial synesthesia electronic material thatsimultaneously implements functions of piezoelectric and light-emittingmaterials is defined as a synchronized piezoelectric and luminescence(SPL) material, and there is a need to develop a single SPL material.

Meanwhile, there have been proposed research in manufacturing acomposite film of perovskite nanocrystal (MAPbX₃)/piezoelectric polymer(polyvinylidene fluoride (PVDF)) through an in-situ method [Adv. Mater.2016, 28, 9163-9168] and research in manufacturing a composite film ofinorganic quantum dots (Cd_(x)Zn_(1-x)Se_(y)S_(1-y))/piezoelectricpolymer (PVDF) through a blade-coating method [ACS Appl. Mater.Interfaces 2018, 10, 15880-15887].

However, in the preceding research, since materials are physically mixedthrough a simple fusion method of two or more single functionalmaterials, there is a limitation in implementing ultra-flexible andultra-low power functions.

SUMMARY

The present invention is directed to providing a single synchronizedpiezoelectric and luminescence (SPL) material simultaneously having apiezoelectric property and a luminescent property by attachingpiezoelectric ligands to light-emitting particles to impart apiezoelectric property to the light-emitting particles, and an elementincluding the same.

According to an aspect of the present invention, there is provided asynchronized piezoelectric and luminescence material including a corelayer including light-emitting particles and a shell layer which isattached onto a surface of the core layer and includes ligands having apiezoelectric property.

According to one embodiment, the light-emitting particles may besurrounded by the plurality of ligands, and some or all of the ligandsmay be ligands having the piezoelectric property.

According to another embodiment, the ligand having the piezoelectricproperty may be attached onto the surface of the core layer through aligand exchange.

The ligand having the piezoelectric property may be represented byFormula 1 below:

wherein, in Formula 1, each of R₁ and R₂ is independently hydrogen (H),iron (F), chlorine (Cl), COOH, COOR, or CF₃, each of R₃ and R₄ isindependently H, OH, SH, SSOR, NH₂, N₃, COOH, Cl, bromine (Br), iodine(I), or an alkynyl group having 1 to 10 carbon atoms, each R isindependently a hydrogen atom, a deuterium atom, a halogen atom, a cyanogroup, a substituted or unsubstituted alkyl group having 1 to 10 carbonatoms, or a substituted or unsubstituted aryl group having 6 to 30 ringcarbon atoms, and n is an integer from 1 to 50,000.

The light-emitting particles may be at least one selected from the groupconsisting of perovskite crystals, silicon (Si)-based crystals, GroupII-VI-based compound semiconductor crystals, Group III-V-based compoundsemiconductor crystals, Group IV-VI-based compound semiconductorcrystals, boron quantum dots, carbon quantum dots, and metal quantumdots.

The perovskite crystals may have a structure of ABX₃(3D), A₄BX₆(0D),AB₂X₅(2D), A₂BX₄(2D), A₂BX₆(0D), A₂B⁺B³⁺X₆(3D), A₃B₂X₉(2D), orA_(n−1)B_(n)X3_(n+1) (quasi-2D), wherein n is an integer of two to six,A refers to a monovalent cation, B refers to a metal material, and Xrefers to a halogen element.

A may be at least one selected from the group consisting of(C_(x)H_(2x+1)NH₃)_(n) ⁺, (C₆H₅C_(x)H_(2x+1)NH₃)_(n) ⁺, (CH(NH₂)₂)_(n)⁺, (NH₄)_(n) ⁺, (NF₄)_(n) ⁺, (NCl₄)_(n) ⁺, (PH₄)_(n) ⁺, (PF₄)_(n) ⁺,(PCl₄)_(n) ⁺, (C(NH₂)₃)_(n) ⁺, ((C_(x)H_(2x+1))_(n)NH₃)₂(CHNH₃)_(n) ⁺,(CF₃NH₃)_(n) ⁺, (C_(x)F_(2x+1))_(n)NH₃)₂(CFNH₃)_(n) ⁺,((C^(x)F_(2x+1))_(n)NH₃)₂ ⁺, (CH₃PH₃)_(n) ⁺, (CH₃AsH₃)_(n) ⁺,(CH₃SbH₃)_(n) ⁺, (AsH₄)_(n) ⁺, (SbH₄)_(n) ⁺, Cs⁺, Rb⁺, and K⁺, wherein nis an integer of one or more, and x is an integer of one or more, B maybe at least one selected from the group consisting of a divalenttransition metal, a rare earth metal, an alkaline earth metal, lead(Pb), tin (Sn), germanium (Ge), gallium (Ga), indium (In), aluminum(Al), antimony (Sb), bismuth (Bi), and polonium (Po), and X may be atleast one selected from the group consisting of chlorine (Cl), bromine(Br), and iodine (I).

The Group II-VI-based compound semiconductor crystals may be at leastone selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe,ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS,HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS,HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe,HgZnSeS, HgZnSeTe, and HgZnSTe.

The Group III-V-based compound semiconductor crystals may be at leastone selected from the group consisting of GaN, GaP, GaAs, AlN, AlP,AlAs, InN, InP, InAs, GaNP, GaNAs, GaPAs, AlNP, AlNAs, AlPAs, InNP,InNAs, InPAs, GaAlNP, GaAlNAs, GaAlPAs, GaInNP, GaInNAs, GaInPAs,InAlNP, InAlNAs, and InAlPAs.

The Group IV-VI-based compound semiconductor crystals may be at leastone selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe,PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe,SnPbSSe, SnPbSeTe, and SnPbSTe.

The carbon quantum dots may be at least one selected from the groupconsisting of graphene quantum dots, carbon quantum dots, C₃N₄syndiotactic quantum dots, and polymer quantum dots.

The metal quantum dots may be at least one selected from the groupconsisting of gold (Au), silver (Ag), aluminum (Al), copper (Cu),lithium (Li), palladium (Pd), and platinum (Pt).

The synchronized piezoelectric and luminescence material may have anemission wavelength of 200 nm to 1,500 nm and a polarization of 0.1μC/cm² to 100 μC/cm².

According to another aspect of the present invention, there is provideda method of preparing a synchronized piezoelectric and luminescencematerial including mixing a solution (a) including light-emittingparticles or precursors thereof and a solution (b) including ligandshaving a piezoelectric property in a polar solvent, and optionally,mixing a solution (c) including ligands having a piezoelectric propertyin an antisolvent together with the solution (a) and the solution (b),if necessary.

According to one embodiment, the method may include mixing the solution(a) and the solution (b), and adding the solution (c) to the resultantmixture.

According to another embodiment, the method may include mixing thesolution (a) and the solution (c) and adding the solution (b) to theresultant mixture to be mixed with each other.

According to still another embodiment of the present invention,hydrophilic monomolecular ligands such as mono-2-(methacryloyloxy)ethylsuccinate (MMES) may be additionally attached to the light-emittingparticles or the precursors thereof in the solution (a).

According to yet another embodiment of the present invention, the ligandin the solution (b) may derive from a fluoride resin such aspolyvinylidene fluoride (PVDF) and may have a structure substituted withH, OH, SH, SSOR, or COOH, wherein R is a hydrogen atom, a deuteriumatom, a halogen atom, a cyano group, a substituted or unsubstitutedalkyl group having 1 to 10 carbon atoms, or a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms.

According to still another aspect of the present invention, there isprovided a synchronized piezoelectric and luminescence material preparedaccording to the method.

According to yet another aspect of the present invention, there isprovided a synchronized piezoelectric and luminescence element includinga substrate, a first electrode disposed on the substrate, alight-emitting layer disposed on the first electrode, and a secondelectrode disposed on the light-emitting layer, wherein thelight-emitting layer includes the synchronized piezoelectric andluminescence material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a synchronized piezoelectricand luminescence material according to one embodiment of the presentinvention.

FIG. 2 shows results obtained by piezoelectric force microscopymeasurement on a perovskite nanoparticle material attached with apiezoelectric ligand according to Example 1 of the present invention.

FIG. 3 shows a polarization history curve of an inorganic quantum dotmaterial attached with a piezoelectric ligand according to Example 3 ofthe present invention.

FIG. 4 shows results obtained by driving an element to which aninorganic quantum dot material attached with a piezoelectric ligandaccording to Example 6 of the present invention is applied.

DETAILED DESCRIPTION

While the present invention is open to various modifications andalternative embodiments, specific exemplary embodiments thereof will bedescribed and illustrated by way of example in the accompanyingdrawings. However, it is to be understood that the present invention isnot limited to a specific disclosed form but includes all modifications,equivalents, and substitutions without departing from the scope andsprit of the present invention.

It will be further understood that the terms “comprise,” “comprising,”“include,” and/or “including,” when used herein, specify the presence ofstated features, numbers, steps, operations, elements, components, orcombinations thereof but do not preclude the presence or addition of oneor more other features, numbers, steps, operations, elements,components, and/or combinations thereof.

In the present specification, the expression “synchronized piezoelectricand luminescence (SPL)” may mean having both a piezoelectric propertyand a luminescent property.

In the present specification, the term “single SPL material” refers toan artificial synesthesia electronic material in which a piezoelectricproperty and a luminescent property are simultaneously implemented usinga single material.

Such a single SPL material may be implemented through various methods,and SPL properties may be implemented in the form of particles includinga core, which is a light-emitting part, and a ligand positioned on asurface of the core.

Accordingly, an SPL material according to the present invention includesa core layer which includes light-emitting particles and a shell layerwhich is attached onto a surface of the core layer and includes ligandshaving a piezoelectric property.

Here, the light-emitting particles may be at least one selected from thegroup consisting of perovskite crystals, silicon (Si)-based crystals,Group II-VI-based compound semiconductor crystals, Group III-V-basedcompound semiconductor crystals, Group IV-VI-based compoundsemiconductor crystals, boron quantum dots, carbon quantum dots, andmetal quantum dots. Specifically, the light-emitting particles may beperovskite crystals or metal quantum dots.

The perovskite crystals may have a structure of ABX₃(3D), A₄BX₆(0D),AB₂X₅(2D), A₂BX₄(2D), A₂BX₆(0D), A₂B⁺B³⁺X₆(3D), A₃B₂X₉(2D), orA_(n−1)B_(n)X3_(n+1) (quasi-2D), wherein n is an integer of two to six,A refers to a monovalent cation, B refers to a metal material, and Xrefers to a halogen element.

In this case, A may be at least one selected from the group consistingof (C_(x)H_(2x+1)NH₃)_(n) ⁺, (C₆H₅C_(x)H_(2x+1)NH₃)_(n) ⁺,(CH(NH₂)₂)_(n) ⁺, (NH₄)_(n) ⁺, (NF₄)_(n) ⁺, (NCl₄)_(n) ⁺, (PH₄)_(n) ⁺,(PF₄)_(n) ⁺, (PCl₄)_(n) ⁺, (C(NH₂)₃)_(n) ⁺,((C_(x)H_(2x-1))_(n)NH₃)₂(CHNH₃)_(n) ⁺, (CF₃NH₃)_(n) ⁺,(C_(x)F_(2x+1))_(n)NH₃)₂(CFNH₃)_(n) ⁺, ((C^(x)F_(2x+1))_(n)NH₃)₂ ⁺,(CH₃PH₃)_(n) ⁺, (CH₃AsH₃)_(n) ⁺, (CH₃SbH₃)_(n) ⁺, (AsH₄)_(n) ⁺,(SbH₄)_(n) ⁺, Cs⁺, Rb⁺, and K⁺, wherein n is an integer of one or more,and x is an integer of one or more. B may be at least one selected fromthe group consisting of a divalent transition metal, a rare earth metal,an alkaline earth metal, lead (Pb), tin (Sn), germanium (Ge), gallium(Ga), indium (In), aluminum (Al), antimony (Sb), bismuth (Bi), andpolonium (Po). X may be at least one selected from the group consistingof chlorine (Cl), bromine (Br), and iodine (I).

The Group II-VI-based compound semiconductor crystals may be at leastone selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe,ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS,HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS,HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe,HgZnSeS, HgZnSeTe, and HgZnSTe.

The Group III-V-based compound semiconductor crystals may be at leastone selected from the group consisting of GaN, GaP, GaAs, AlN, AlP,AlAs, InN, InP, InAs, GaNP, GaNAs, GaPAs, AlNP, AlNAs, AlPAs, InNP,InNAs, InPAs, GaAlNP, GaAlNAs, GaAlPAs, GaInNP, GaInNAs, GaInPAs,InAlNP, InAlNAs, and InAlPAs.

The Group IV-VI-based compound semiconductor crystals may be at leastone selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe,PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe,SnPbSSe, SnPbSeTe, and SnPbSTe.

The carbon quantum dots may be at least one selected from the groupconsisting of graphene quantum dots, carbon quantum dots, C₃N₄syndiotactic quantum dots, and polymer quantum dots.

The metal quantum dots may be at least one selected from the groupconsisting of gold (Au), silver (Ag), aluminum (Al), copper (Cu),lithium (Li), palladium (Pd), and platinum (Pt).

Meanwhile, representative high luminous efficiency particles includeGroup II-VI- or III-V-based semiconductor crystals and perovskiteparticles. The Group II-VI- or III-V-based semiconductor crystals mayadjust a color by adjusting a particle size using a quantum confinementeffect, may implement high color purity (full width at half maximum(FWHM)≈30 nm) as compared with an organic luminous material, and mayhave a particle size of several nanometers. Since metal halideperovskite particles have high color purity (FWHM<25 nm) due to acrystal structure thereof irrespective of a particle size, coloradjustment thereof is simple, and synthesis costs thereof are low, themetal halide perovskite particles are very likely to be developed asluminous materials.

However, nanoparticles used as luminous materials may have a largesurface-to-volume ratio due to a small particle size of severalnanometers to several tens of nanometers and thus may have a high defectconcentration. Therefore, there is an essential need to developtechnology capable of simultaneously effectively controlling defectsthat may be formed in surfaces of nanocrystals as well as inside ofnanoparticles.

Particles are distinguished from grains. Most of the particles arecolloidal particles of which one particle acts independently and whichare synthesized and obtained in a solution state. Even in this case,ligands surrounding the particles are present due to chemical action inmost cases. Grains surround particles in a polycrystalline thin film,form a grain boundary without a ligand, are connected to each other, andare mainly formed into a polycrystalline thin film by reacting directlyfrom a precursor. Here, one grain may look just like a particle, but inthis case, the particle being regarded as a grain is accurate, and sinceone grain cannot be separately defined, the grain is not regarded as aparticle. In the case of particles, when a ligand is not present, theparticles are all deposited within several hours and thus may not bestably dispersed. As a ligand, small molecules, which serve assurfactants, are mainly used. In this case, the ligand may prevent thephysical contact between particles and passivate the surface defects toimprove the stability and luminescent property of the particles and mayimpart the specific properties to the particles by adjusting adispersion solvent or the like according to the properties of theligand.

Meanwhile, the present invention is characterized by providing amaterial simultaneously having a piezoelectric property and aluminescent property by attaching ligands to light-emitting particles toimpart a piezoelectric property to the particles, and an elementincluding the same.

That is, the light-emitting particles according to the present inventionmay be surrounded by the plurality of ligands, and some or all of theligands may be ligands having a piezoelectric property.

In this case, the ligand having a piezoelectric property may berepresented by Formula 1 below.

In Formula 1, R₁ and R₂ may each independently be hydrogen (H), iron(F), chlorine (Cl), COOH, COOR, or CF₃, more specifically may be H, F,or Cl, and still more specifically may be H or F.

R₃ and R₄ may each independently be H, OH, SH, SSOR, NH₂, N₃, COOH, Cl,bromine (Br), iodine (I), or an alkynyl group having 1 to 10 carbonatoms, and more specifically, may be H, OH, SH, SSOR, or COOH.

Each R may independently be a hydrogen atom, a deuterium atom, a halogenatom, a cyano group, a substituted or unsubstituted alkyl group having 1to 10 carbon atoms, or a substituted or unsubstituted aryl group having6 to 30 ring carbon atoms, and more specifically, may be a hydrogen atomor a substituted or unsubstituted alkyl group having 1 to 10 carbonatoms. Here, the alkyl group and the aryl group may be substituted witha halogen atom.

n may be an integer from 1 to 50,000.

According to one embodiment of the present invention, in Formula 1, R₁and R₂ may each independently be H, F, or Cl, R₃ and R₄ may eachindependently be H, OH, SH, SSOR, or COOH, and R may be a hydrogen atomor a substituted or unsubstituted alkyl group having 1 to carbon atoms.

In this case, the ligand having a piezoelectric property represented byFormula 1 may be any one selected from among compounds shown in compoundgroup 1 below. However, embodiments are not limited thereto.

In compound group 1, each R is independently a hydrogen atom, adeuterium atom, a halogen atom, a cyano group, a substituted orunsubstituted alkyl group having 1 to 10 carbon atoms, or a substitutedor unsubstituted aryl group having 6 to 30 ring carbon atoms, X is F,Cl, Br, or I, and n is an integer of 1 to 50,000.

Meanwhile, the ligand having a piezoelectric property may be any oneselected from among compounds shown in compound group 2 below. However,embodiments are not limited thereto.

In compound group 2, each R may independently be a hydrogen atom, adeuterium atom, a halogen atom, a cyano group, a substituted orunsubstituted alkyl group having 1 to 10 carbon atoms, or a substitutedor unsubstituted aryl group having 6 to 30 ring carbon atoms, and n maybe an integer from 1 to 50,000.

The ligand having a piezoelectric property represented by Formula 1 mayderive specifically from a fluoride resin such as polyvinylidenefluoride (PVDF) and may have a structure substituted with H, OH, SH,SSOR, or COOH.

The “substituted or unsubstituted alkyl group having 1 to 10 carbonatoms” may be a branched or linear alkyl group, may be substituted witha halogen atom, COOH, or CF₃, and specifically may be unsubstituted.

The “substituted or unsubstituted aryl group having 6 to 30 ring carbonatoms” may be substituted with a halogen atom, COOH, or CF₃ andspecifically may be unsubstituted.

Specifically, each R may be independently a hydrogen atom, a halogenatom, or substituted or unsubstituted alkyl group having 1 to 10 carbonatoms.

As described above, the material according to the present inventionincludes the shell layer formed by attaching the ligands having apiezoelectric property to the surface of the core layer including theluminous particles, thereby simultaneously implementing a piezoelectricproperty and a luminescent property. Specifically, the SPL materialaccording to the present invention has a wide emission wavelength of 200nm to 1,500 nm and a polarization of 0.1 μC/cm² to 100 μC/cm².

Therefore, since the SPL material according to the present invention hasa piezoelectric property and a luminescent property at the same time,the SPL material can be applied to efficient communication byvisualizing various input signals, such as sound, touch, and temperaturesignals, thereby being usefully used for a next-generationfuture-oriented wearable synesthesia element.

The synesthesia element includes various elements used in all fieldssuch as industrial, commercial, medical, vehicle, and personnel computer(PC) fields. As an example of the synesthesia element, there may be astretchable device. Since an existing photoelectric element ismanufactured on a stretchable substrate, the stretchable device can beoperated even when the substrate is contracted or stretched, and thus,various application fields thereof may be created. In addition, thestretchable device may be variously used as a core component materialfor implementing wearable electronic devices, electronic skins, Internetof Things (IoT) devices, electronic devices for a vehicle, andartificially intelligent (AI) robots.

As an example, the SPL material according to the present invention maybe applied to a light-emitting layer of a light-emitting element. Such alight-emitting element includes a substrate, a first electrode disposedon the substrate, a light-emitting layer disposed on the firstelectrode, and a second electrode disposed on the light-emitting layer,and the light-emitting layer includes the SPL material according to thepresent invention.

The substrate may be a flexible substrate, and the flexible substratemay be, for example, a polyimide substrate or a polyethylene naphthalate(PEN) substrate.

The first electrode layer and the second electrode layer may include atleast one selected from the group consisting of gold, silver, copper,graphene, silicon nanowires, carbon nanotubes, and indium tin oxide.

According to one embodiment of the present invention, the light-emittingelement of the present invention may further include one or moreadditional layers such as a hole injection layer, a hole transportlayer, a conductive layer, a nonconductive layer, an electron transportlayer, an electron injection layer, and a capping layer.

According to another embodiment of the present invention, thelight-emitting element may be used in a wearable electronic device, anelectronic skin, or an electronic device for a vehicle.

Hereinafter, the present invention will be described in detail throughExamples, but the following Examples and Experimental Examples onlyexemplify one form of the present invention, and the scope of thepresent invention is not limited by the following Examples andExperimental Examples.

[Example 1] Preparation of Ligand-Attached Perovskite NanoparticleSolution and Manufacturing of Film

A precursor solution (solution 1) was prepared by dissolving a metalhalide perovskite in a polar solvent. In this case, dimethylformamidewas used as the polar solvent, and formamidinium bromide (FABr) andPbBr₂ were used as a metal halide perovskite precursor. In this case,FABr and PbBr₂ were used in a ratio of 2:1. Thereafter, a polar solution(solution 2) including a piezoelectric ligand was prepared. In thiscase, dimethylformamide (DMF) was used as the polar solvent, andPVDF-COOH was used as the piezoelectric ligand. In this case, aconcentration of the PVDF-COOH ligand in the solution was set to 10 wt%. Thereafter, an anti-solvent solution (solution 3) including a ligandwas prepared. As a solvent for the anti-solvent solution, a solvent inwhich toluene and 1-butanol were mixed was used, and a mixing ratio ofthe mixed solvent was 5:2. As the ligand, an oleic acid and octyl aminewere used. Thereafter, solution 1 and solution 2 were mixed and thendropped into solution 3 to induce crystallization of metal halideperovskite nanoparticles. As the precursor solution of the metal halideperovskite was mixed with the anti-solvent solution, solubility thereofwas rapidly decreased, and as a result, a metal halide perovskitecrystal surrounded by a ligand including a piezoelectric ligand wasprecipitated.

After such a prepared metal halide perovskite nanoparticle solution isapplied on a glass substrate, spin coating was performed on the glasssubstrate rotating at a speed of 500 rpm, thereby manufacturing aperovskite film.

[Example 2] Method of Preparing Particles Through Ligand Exchange andManufacturing of Film

A precursor solution (solution 1) was prepared by dissolving a metalhalide perovskite in a polar solvent. In this case, DMF was used as thepolar solvent, and FABr and PbBr₂ were used as a metal halide perovskiteprecursor. In this case, FABr and PbBr₂ were used in a ratio of 2:1.Thereafter, a polar solution (solution 2) including a piezoelectricligand was prepared. In this case, DMF was used as the polar solvent,and PVDF-COOH was used as the piezoelectric ligand. In this case, aconcentration of the PVDF-COOH ligand in the solution was set to 10 wt%. Thereafter, an anti-solvent solution (solution 3) including a ligandwas prepared. As a solvent for the anti-solvent solution, a solvent inwhich toluene and 1-butanol were mixed was used, and a mixing ratio ofthe mixed solvent was 5:2. As the ligand, an oleic acid and octyl aminewere used. Thereafter, solution 1 was dropped into solution 3 to inducecrystallization of metal halide perovskite nanoparticles. As theprecursor solution of the metal halide perovskite was mixed with theanti-solvent solution, solubility thereof was rapidly decreased, and asa result, a metal halide perovskite crystal surrounded by a ligand wasprecipitated. Thereafter, solution 2 was injected into a solutionincluding the precipitated perovskite crystal to induce a ligandexchange to attach a piezoelectric ligand onto a surface of theperovskite crystal. In this case, an injected amount of solution 2 was50 μl.

After such a prepared metal halide perovskite nanoparticle solution isapplied on a glass substrate, spin coating was performed on the glasssubstrate while the glass substrate was rotating at a speed of 500 rpm,thereby manufacturing a perovskite film.

[Example 3] Preparation of Piezoelectric Ligand-Attached Quantum DotSolution and Manufacturing of Film

A polar solution (solution 1) including a hydrophilic monomolecularligand was prepared. In this case, propylene glycol methyl ether acetate(PGMEA) was used as a polar solvent, and mono-2-(methacryloyloxy)ethylsuccinate (MMES) was used as the hydrophilic monomolecular ligand. Inthis case, a concentration of the MMES ligand in the solution was set to5 mg/mL. Thereafter, a nonpolar solution (solution 2) includinginorganic quantum dots was prepared. In this case, hexane was used as anonpolar solvent, and inorganic quantum dots attached with an oleic acidwere used. In this case, a concentration of the inorganic quantum dotsin the solution was set to 5 mg/ml. Thereafter, solution 2 was mixedwith solution 1 to form a mixed solution (solution 3). Solution 3 wasstirred for 10 minutes to attach the MMES to the inorganic quantum dots.Then, the inorganic quantum dots were precipitated in a cold hexanesolvent. Thereafter, a polar solution (solution 4) including apiezoelectric ligand was prepared. In this case, DMF was used as a polarsolvent, and PVDF-SH was used as the piezoelectric ligand. Here, aconcentration of the PVDF-SH ligand in the solution was set to 20 mg/mL.Thereafter, the solution was stirred for 12 hours or more to attach thePVDF-SH ligand to the inorganic quantum dots. Then, the inorganicquantum dots were precipitated in a cold hexane solvent and dispersedagain in DMF. As a result, inorganic quantum dots (PVDF-QDs) surroundedby ligands including piezoelectric ligands were prepared.

After such an inorganic quantum dot solution is applied on a glasssubstrate, spin coating was performed on the glass substrate rotating ata speed of 500 rpm, thereby manufacturing an inorganic quantum dot film.

[Example 4] Manufacturing of Perovskite Element

First, after an indium tin oxide (ITO) substrate (glass substrate coatedwith an ITO positive electrode) was provided, spin coating was performedon the ITO positive electrode with a conductive material PEDOT:PSS(AI4083 manufactured by Heraeus Company), and then heat treatment wasperformed thereon at a temperature 150° C. for 30 minutes to form anhole injection layer having a thickness of 50 nm.

Next, the perovskite nanoparticle solution attached with a piezoelectricligand prepared in Example 1 was applied on the hole injection layer,and spin coating was performed on the hole injection layer rotating at aspeed of 500 rpm, thereby forming a light-emitting layer having athickness of 50 nm.

Thereafter, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) wasdeposited to a thickness of 50 nm on the perovskite light-emitting layerat a high vacuum of 1×10⁻⁷ Torr or less to form an electron transportlayer, LiF was deposited to a thickness of 1 nm on the electrontransport layer to form an electron injection layer, and aluminum wasdeposited to a thickness of 100 nm on the electron injection layer toform a negative electrode, thereby manufacturing a perovskitelight-emitting diode.

[Example 5] Manufacturing of Perovskite Inverted Element

First, after an ITO substrate (glass substrate coated with an ITOnegative electrode) was provided, spin coating was performed on the ITOnegative electrode with a semiconductor material ZnO, and heat treatmentwas performed thereon at a temperature 150° C. for 1 hour to form anelectron injection layer having a thickness of 60 nm.

Next, spin coating was performed on the electron injection layer withpolyvinylpyrrolidone (PVP), and then heat treatment was performedthereon at a temperature of 100° C. for 10 minutes to form anon-conductor layer having a thickness of 10 nm.

Then, the perovskite nanoparticle solution attached with a piezoelectricligand prepared in Example 2 was applied on the electron injectionlayer, and spin coating was performed on the electron injection layerrotating at a speed of 500 rpm to form a perovskite light-emittinglayer.

Thereafter, tris(4-carbazoyl-9-ylphenyl)amine (TCTA) was deposited to athickness of 50 nm on the perovskite light-emitting layer at a highvacuum of 1×10⁻⁷ Torr or less to form a hole transport layer, and MoO₃was deposited to a thickness of 5 nm on the hole transport layer to forma hole injection layer.

Silver was deposited to a thickness of 100 nm on the hole injectionlayer to form a positive electrode, thereby manufacturing a perovskitelight-emitting diode.

[Example 6] Manufacturing of PVDF-QD Element

First, after an ITO substrate (glass substrate coated with an ITOnegative electrode) was provided, a cleaning process was performed usingeach of acetone and isopropyl alcohol (IPA) solutions to preparemanufacturing of a diode. In order to form a thin film of electrontransport layer material ZnO on the ITO negative electrode, zinc acetatedihydrate was dissolved in an ethanol solvent, spin coating wasperformed, and heat treatment was performed at a temperature of 140° C.to form an electron transport layer having a thickness of several tensof nanometers. Next, in order to adjust band gap energy between the ZnOthin film and an organic light-emitting layer in which a polymermaterial (PDVF) and quantum dots (CdSe⁻Zn_(1-x)Cd_(x)S) are synthesized,a polyethylenimine (PEI) solution was applied on the electron transportlayer, and spin coating was performed on the electron transport layerrotating at a speed of 5,000 rpm. A manufactured thin film washeat-treated at a temperature of 100° C. for 10 minutes to form a thinfilm having a thickness of several nanometers.

Thereafter, an organic light-emitting material, i.e., the PVDF-QDssynthesized in Example 3, was dissolved in a DMF solution and applied ona thin film layer of such an element, and spin coating was performed onthe thin film layer rotating at a speed of 1,000 rpm to form a thin filmlayer of several nanometers. Then, WO₃ was deposited to a thickness of15 nm on an organic light-emitting layer at a high vacuum of 1×10⁻⁷ Torror less to form a hole transport layer, and Al was deposited to athickness of 70 nm on the hole transport layer to form a positiveelectrode, thereby manufacturing a light-emitting diode.

[Comparative Example 1] Manufacturing of Perovskite Nanoparticle Film

After a metal halide perovskite nanoparticle solution is applied on aglass substrate, spin coating was performed on the glass substraterotating at a speed of 500 rpm, thereby manufacturing a perovskite film.

Experimental Example

In order to evaluate the luminescent property, ferroelectricity, andpiezoelectric property of the materials according to Examples, thefollowing experiment was performed.

First, piezoelectric force microscopy measurement was performed on aperovskite nanoparticle material attached with a piezoelectric ligandaccording to Example 1, and the results were shown in FIG. 2 . As can beseen from FIG. 2 , it can be seen that the perovskite nanoparticlematerial attached with a piezoelectric ligand according to Example 1 hasa piezoelectric property.

In addition, a polarization history curve of an inorganic quantum dotmaterial attached with a piezoelectric ligand according to Example 3 wasderived, and the results were shown in FIG. 3 . Referring to FIG. 3 , itcan be seen that the inorganic quantum dot material attached with apiezoelectric ligand according to Example 3 has an excellentpiezoelectric property.

In addition, the driving result of an element (Example 6) to which theinorganic quantum dot material attached with a piezoelectric ligandaccording to Example 3 is applied is shown in FIG. 6 , and it can beseen that the material also has a high luminescent property.

As a result, it can be seen that an electronic element including the SPLmaterial according to the present invention has the excellentluminescent property, ferroelectricity, and piezoelectric property. Fromthe results, the SPL material according to the present invention mayexhibit the excellent luminescent property, ferroelectricity, andpiezoelectric property, and it can be seen that an electronic elementincluding the same can be usefully used for an organic light-emittingelement, a transistor, a capacitor, and the like.

A material according to the present invention is a single SPL materialin which piezoelectric ligands and light-emitting particles arechemically coupled, thereby simultaneously implementing a piezoelectricproperty and a luminescent property. In addition, an element based onthe material can be manufactured, and an element system simultaneouslyhaving a piezoelectric property and a luminescent property can bedesigned through the element.

Accordingly, an element including the material can perform efficientcommunication by visualizing various input signals, thereby beingusefully used in a future-oriented synesthesia technology field. Inaddition, since the element including the material is an all-in-oneelement, additional components and processes are not required, and thus,the element has high economic competitiveness, thereby contributinggreatly to the commercialization of synesthesia elements.

While the present invention has been described with reference to theexemplary embodiments thereof, it will be appreciated by those skilledin the corresponding art or those having ordinary knowledge in thecorresponding art that the present invention may be modified and alteredin various manners without departing from the spirit and technical scopeof the present invention that are set forth in the following claims.

Therefore, the technical scope of the present invention should not belimited to the contents described in the detailed description of thespecification but should be defined by the claims.

What is claimed is:
 1. A method of preparing a synchronizedpiezoelectric and luminescence material, the method comprising: mixing asolution (a) including light-emitting particles or precursors thereofand a solution (b) including ligands having a piezoelectric property ina polar solvent; and optionally, mixing a solution (c) including ligandshaving a piezoelectric property in an antisolvent together with thesolution (a) and the solution (b), if necessary.
 2. The method of claim1, wherein the method includes: mixing the solution (a) and the solution(b); and adding the solution (c) into the resultant mixture to be mixedwith each other.
 3. The method of claim 1, wherein the method includes:mixing the solution (a) and the solution (c); and adding the solution(b) into the resultant mixture to be mixed with each other.
 4. Themethod of claim 1, wherein the ligand in the solution (b) derives from afluoride resin and has a structure substituted with H, OH, SH, SSOR, orCOOH, wherein R is a hydrogen atom, a deuterium atom, a halogen atom, acyano group, a substituted or unsubstituted alkyl group having 1 to 10carbon atoms, or a substituted or unsubstituted aryl group having 6 to30 ring carbon atoms.
 5. The method of claim 1, wherein the synchronizedpiezoelectric and luminescence material has an emission wavelength of200 nm to 1,500 nm and a polarization of 0.1 μC/cm² to 100 μC/cm².